Dressing machine



June 25, 1946.

J. A. COSTELOW DRESSING MACHINE Filed July 14', 1944 INVENTOR,

n ma w Patented June 25, 1946 UNITED STATES PATENT OFFICE 2,402,734 DRESSING MACHINE John A. Costelow, Topeka, Kans.

Application July 14, 1944, Serial No. 544,925

. 4 Claims. 1

My invention relatesto improvements in dressingmachines.

I The object of: my. invention isto provide a dressing machine, the function of which is to produce a rounded edge on rectangular, waferlike. quartz pieces. such. as piezoelectric crystals. The dressing of the edges of the crystals is accomplished by submitting them to the action of an abrasive belt, the movement of which is in the direction of the plane of the faces of the crystals while rocking the said crystals, and thereby reduce inaccuracies in their calibration.

These and other objects will hereinafter be more fully explained. Referring to the drawing in which like characters apply to like parts in the different views:

Fig. 1 is an elevation of the dressing machine.

Fig. 2 is a plan view of the dressing machine, in which the driving motor, drums, and supporting structural parts are not shown.

Fig. 3 is a side view of the dressing machine illustrating the frame assembly and reciprocating motor, some parts shown in section and some parts removed.

Fig. 4 is an enlarged, partial sectional view, showing the relation of the stationar and reciprocating frames, abrasive belt and some of the crystals in place. The latter is shown at the extreme position to the left.

Fig. 5 is the same view as that shown in Fig. 4, excepting that the crystals are shown at the extreme position to the right,

Fig. 6 is a sectional view taken on line 6-6 in Fig. 5.

Fig. '7is an elevation of a crystal of the kind described showing its general shape.

Fig. 8 is a greatly enlarged sectional portion of a crystal illustrating an edge before and after dressing.

The conventional buffing or dressing machine shown comprises a base I, a driving motor 2, a driving belt 3, a driven drum 4, an idler drum 5, an abrasive belt 6, and a table 1. Two angles 8 and B are aflixed to the under side of the table 1 by means of the bolts 9 and 9' and extend beyond the said table in the manner shown in Fig. 2 and Fig. 3.

The lower or stationary frame of the mechanism, comprising the angles I and I0 connected at one end by the crossbar I I, at an intermediate point adjacent to the edge of the belt by a crossbar I2, and at the other end by a crossbar I3, is supported on the angles 8 and 8 in the manner shown in Fig. 3 at A and B. Longitudinal bars I 4, equally spaced between the angles I9 and II), are each fastened to the crossbar I2 at one end and to the crossbar I3 at: the other end. Rods I5, equally spaced, areconnected between the longitudinal bars 14; and also between the longitudinal bars adjacent to the angles It and I0 and the said angles. 7

An upper or movable frame is constructed in a manner similar to that of the lower frame and is slideably mounted thereon. The upper frame consists of the crossbars I6 and I1, which rest upon and are firmly aflixed to the longitudinal bars I8. The rods I9 are equally spaced and connected between the bars I8 as shown. The reciprocating motor 20, mounted on crossbar II, rotates the disk 2|. A link 22 is connected to the disk 2| by the pin 23 at one end and to the slotted link 24, at the other end, by the pin 25. The slotted link 24 is rigidly conected to the rod 26, which is trunnioned in the angles Ill and Ill. The two arms 21 and 21' are rigidly connected at one end to the rod 26.

Arms 28 and 28' are connected to the arms 21 and 21, respectively, by the pins 29 and 29' at one end. At the other end, the arms 28 and 28' are connected to the members 30 and 30, respectively, by means of pins 3| and 3I'. The member 30 is rigidly afiixed to the bar I8, adjacent to the angle Ill; and the member 30 is connected to the bar I8, adjacent to the angle III.

The quartz crystals 32 are placed in the machine in the manner illustrated in Figs. 4, 5, and 6. As herein stated, the driving motor 2 propels the abrasive belt. The reciprocating motor 20 reciprocates the upper frame by means of the connecting links and arms shown and described. The reciprocation of the upper frame rocks the upper edges of the crystals through an arc. The left limit of motion of the crystals is shown in Fig. 4 and the right limit of motion is shown in Fig. 5. The movement described rolls the edge of a crystal in contact with the abrasive belt, reducing the original sharp rectangular corners to a rounded edge as shown at C in Fig. 8. The rounded ground edge is required to prevent chipping.

The occurrence of chipping at the edges of a crystal of the kind described introduces serious inaccuracies in its frequency and activity at basic temperatures. Formerly, the edge grinding operation was performed by hand. The dressing machine described provides a faster means of dressing the edges of the crystals, and also results in a much higher percentage of accurately calibrated crystals than the hand method.

The number of longitudinal bars used may be increased or decreased, according to the expediency of operation; and the spacing of such bars may be varied to accommodate different sizes of crystals. Such modifications may be employed as lie within the scope of the appended claims and what I claim as new and desire to secure by Letters Patent is:

1. In an edge dressing machine, an abrasive belt, two frames mounted over said belt, one frame slideably mounted on the other frame, corresponding interstices provided in both of the said frames, said interstices arranged to receive material, wafer-like in shape, the edges of which are subjected to the action of the abrasive belt, means, comprising a, motor and connecting linkage, for imparting reciprocating motion to the upper frame.

2. In an edge dressing machine for crystal wafers, two frames, an abrasive belt, the frames having relative reciprocating motion and positioned adjacent to the belt, corresponding interstices in the frames to receive certain wafers, the edges of which contact the abrasive belt, a, motor and linkage providing means for the reciprocation of the frames thereby imparting a rocking motion to the wafers in order to round the edges thereof.

3. In an edge dressing machine, an upper frame, a lower frame, an abrasive belt, the 'upper frame slideably positioned on the lower frame, the lower frame positioned adjacent to the abrasive belt, longitudinal bars attached to crossbars in the lower frame, rods spaced apart and aflixed to adjacent bars in the upper frame, the rods and bars providing space to receive crystal wafers, the crystal wafers resting on the abrasive belt, means comprising a 'motor and connecting links for relatively reciprocating the said frames.

4. In a dressing machine, an upper frame, a lower frame, an abrasive belt grinder, the upper frame slideably mounted on the lower frame means to reciprocate the said upper frame, corresponding spaces in the upper and lower frames, the said frames positioned above the said grinder, the corresponding spaces receiving certain wafers, the edges of which. contact the grinder, the reciprocation of the frames imparting a rocking motion to the wafers.

JOHN A. COS'IELOW. 

